van Ham J J, Yeo C H
Department of Anatomy and Developmental Biology, University College London, United Kingdom.
Exp Neurol. 1996 Dec;142(2):217-25. doi: 10.1006/exnr.1996.0193.
We have analyzed the afferent limb of the eyeblink and nictitating membrane response of the rabbit by tracing the central distribution of primary afferents from the periorbital skin, conjunctiva, and cornea using horseradish peroxidase agglutinated to wheat germ (WGA-HRP) or conjugated to choleragenoid (B-HRP) as transganglionic tracers. Afferents in the periorbital skin and conjunctiva distribute most heavily to pars caudalis of the spinal trigeminal nucleus (Vc) and to the dorsal horn of spinal segment C1 (dhC1). These afferents terminate predominantly in laminae IIo and IIi and more weakly to the adjacent laminae I and III. There are much weaker projections to spinal segment C2, rostral Vc, and adjacent reticular formation (laminae IV and V) and to the lateral part of pars interpolaris of the spinal trigeminal nucleus (Vi). No conjunctival primary afferents were seen in the rostral divisions of the trigeminal system. Weak afferent inputs from the periorbital skin are present ventrally in pars oralis of the spinal trigeminal nucleus (Vo) and in the principal trigeminal nucleus (Vp). Corneal afferents distribute most densely in the ventral part of Vi and in islands of neuropil within the trigeminal tract at the level of Vi. They also project to caudal Vc and the adjacent dhC1 in laminae I, II, and III. There are sparse projections to the ventral and dorsal parts of Vp and to the ventral part of Vo. Reticular areas adjacent to ventral Vi also receive a few corneal afferents. WGA-HRP- and B-HRP-labeled terminals were distributed similarly in most areas, but lamina I of Vc received terminals labeled with WGA-HRP and Vp and Vo received cutaneous afferents labeled with B-HRP only. Since all subdivisions of the trigeminal system receive periocular and corneal afferent inputs, we suggest that all these subdivisions may be involved in reflex eyeblinks in the rabbit.
我们通过使用凝集到小麦胚芽的辣根过氧化物酶（WGA-HRP）或与霍乱类毒素结合的辣根过氧化物酶（B-HRP）作为跨神经节示踪剂，追踪来自眶周皮肤、结膜和角膜的初级传入神经的中枢分布，分析了家兔眨眼和瞬膜反应的传入支。眶周皮肤和结膜中的传入神经主要分布于三叉神经脊束核尾侧部（Vc）和脊髓C1节段背角（dhC1）。这些传入神经主要终止于IIo层和IIi层，向相邻的I层和III层的投射较弱。向脊髓C2节段、Vc吻侧部、相邻网状结构（IV层和V层）以及三叉神经脊束核极间部外侧部（Vi）的投射则弱得多。在三叉神经系统的吻侧部未见到结膜初级传入神经。眶周皮肤的弱传入输入见于三叉神经脊束核口侧部（Vo）腹侧和三叉神经主核（Vp）。角膜传入神经最密集地分布于Vi腹侧部以及Vi水平三叉神经束内的神经毡岛。它们也投射至尾侧Vc以及I、II和III层的相邻dhC1。向Vp腹侧和背侧部以及Vo腹侧部有稀疏投射。与Vi腹侧相邻的网状区域也接受少量角膜传入神经。WGA-HRP和B-HRP标记的终末在大多数区域分布相似，但Vc的I层接受WGA-HRP标记的终末，而Vp和Vo仅接受B-HRP标记的皮肤传入神经。由于三叉神经系统的所有亚核均接受眼周和角膜传入输入，我们认为家兔的所有这些亚核可能均参与眨眼反射。
